This invention relates to a variable-speed bicycle, and more particularly to the type of a bicycle equipped with a multi-stage freewheel assembly and a cooperating rear deraileur.
As is well known, a conventional multi-stage freewheel assembly having four or more sprocket wheels is too large in dimension to be housed within a conventional gear case. Further, a conventional rear derailleur is also too large in dimension to be housed in a gear case of a conventional size because of difficulty in designing its chain shifting mechanism to be compact and thin without destroying the desired function of the rear derailleur. It is, of course, possible to provide such a large gear case as specially designed for housing both the conventional multi-stage freewheel assembly and rear derailleur of large dimensions. However, a bicycle equipped with such a large gear case will surely not be aesthetically attractive and will not sell well. Therefore, it has been customary that a bicycle equipped with a rear derailleur is never provided with a full-cover type gear case. This ignores a need which arises, for example, from such viewpoints as prevention of exposure to rain and dust, and danger of catching a cyclist's clothing. The inventor is not aware of any prior art proposing a bicycle having a rear derailleur housed within a gear case.
It is, therefore, a primary object of the present invention to provide a bicycle having a two or three-stage freewheel assembly and a rear derailleur both housed within a gear case.
Another object of the invention is to provide a specific construction of a rear derailleur capable of being housed within a gear case.
A further object of the invention is to provide a novel rear derailleur which is relatively simple in construction, compact in size, inexpensive to manufacture and efficient in use.
Other objects, features and advantages of the invention will become apparent from the detailed description given hereinafter in connection with the accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.